Gensets are used extensively for power generation in locomotives, trucks, recreational vehicles), marine vessels as well as for grid power generation. Gensets normally include a prime mover such as an internal combustion engine which converts fossil fuel into mechanical energy to rotate a generator which converts it into useable electrical energy at a line voltage and frequency most suitable for transmission and utilization. The voltage and frequency are two of the most critical operational parameters of a genset's output and they must be monitored and controlled, usually by a digital microcontroller. Voltage signals from generators' outputs must be safely and accurately communicated to the controller for it to maintain stable output from the generator set.
Normal industrial line voltages in the United States are a nominal 480 volts AC which is extremely hazardous to touch and must be enclosed to guard against accidental contact in contrast to modern microcontrollers that operate at very low (5 volts or less) DC levels. In addition, the electrical power circuits and busses into which such gensets are wired can often deliver extremely high currents into short circuits which can produce dangerous arc flashes when an electrical fault occurs. Such currents and flashes can vaporize wiring causing lethal blast injuries to personnel performing routine maintenance operations on the genset or measuring output voltages and load. Therefore it is mandatory to provide adequate isolation between the high AC output voltages inside the generator enclosure and the low microcontroller levels or personnel access port.
Historically gensets used sets of three potential transformers to step output voltages produced by a genset down to the levels a controller or service personnel could safely utilize. However, such potential transformers tend to be relatively large and expensive, adding to both the cost of the generator set's control package and the volume of the enclosure where they are mounted. Alternatively, passive voltage dividers have also been used, but they must dissipate significant power in the form of heat and can require more space than a potential transformer.